NSI-189: A Nootropic Antidepressant That Promotes Neurogenesis

The use of antidepressant medications in America is a rapidly growing portion of the pharmaceutical industry. The number of people who take antidepressants has increased by almost 400% from 1990 through 2008.[1] In addition, eleven percent of Americans aged 12 years and older take some form of antidepressant medication.

Antidepressants have long been a troubled group of drugs in terms of side-effects, with even the most recent class of antidepressants (SSRIs) exhibiting potential side-effects like insomnia, sexual dysfunction, or even worsened depression. These troublesome side-effects have displayed a clear need for more effective treatment options.

Despite the apparent need for a more effective class of antidepressants, no new major milestones have occurred regarding antidepressants since 1987, the year fluoxetine (Prozac) was approved by the FDA.[2] Since the beginning of Prozac’s use to treat depression, SSRIs have dominated the area of medical treatment for depression. This era of depression treatment has been going on for about 29 years. However, some progress is being made in the development of new antidepressants. One of the newest experimental drugs for depression, NSI-189, also displays nootropic properties. Here we will be examining some of the claims surrounding the purported benefits of NSI-189.

Origins of NSI-189

NSI-189 is an experimental drug currently being developed and studied by Neuralstem Inc., a biotechnology company that commercially produces neural stem cells for therapy.[3] The research and development of NSI-189 began in the 1990s, during the years of Bill Clinton’s presidency.

The Clinton administration contracted Neuralstem to research the possibilities of creating a “super soldier,” one that was able to stay awake and alert for extended periods of time.[4] The researchers at Neuralstem recognized that a drug targeting the hippocampus could possibly alleviate the effects of sleep deprivation and exhaustion, and set out to find a drug that could induce neurogenesis. Neuralstem, finding their prospects to be promising, continued research in this vein even after the government program was canceled.

This preliminary research would eventually result in the drug NSI-189. Clinical research on NSI-189 has been in the works since 2011, and a phase 1b trial was completed in July of 2014.[5] Clinical phase 1 trials typically focus on finding the correct dosage range of the drug, which has been placed around 40 to 80 mg per day in the treatment of Major Depressive Disorder (MDD) and cognitive decline.

Chemically speaking, NSI-189 is classified as a small-molecule benzylpiperazine-aminopyridine drug, making it structurally unique among other antidepressants. However, the drug has also seen increased interest in terms of its ability to stimulate nerve growth in the hippocampus.

According to the official Neuralstem, Inc. press release concerning the phase 1b trial, “[NSI-189] is a proprietary new chemical entity that stimulates new neuron growth in the hippocampus, a region of the brain believed to be implicated in MDD, as well as other diseases and conditions such as traumatic brain injury (TBI), Alzheimer’s disease, and post-traumatic stress disorder (PTSD).”[6]

The phase 1b trial of NSI-189 was “a randomized, double-blind, placebo-controlled, multiple-dose escalating trial evaluating the safety, tolerability, pharmacokinetics and pharmacodynamic effect of NSI-189 in the treatment of MDD.” Now that the trial has been completed, the results have been released, and they appear quite promising.

The study, which was conducted on 24 patients over the course of 28 days, found that NSI-189 administration reduced the symptoms of depression and cognitive decline significantly more than placebo. The drug was tolerated well by the subjects, and it “may also exhibit pro-cognitive properties associated with increases in prefrontal alpha coherence.” [7][8]

Mechanism of Action

Selective serotonin reuptake inhibitors (SSRIs) attempt to treat depression by increasing levels of serotonin in the brain. This model of depression, known as the “monoamine hypothesis,” states that depression is caused by a shortage or imbalance of certain neurotransmitters in the depressed patient, mainly serotonin. However, this model has been quite drastically debunked in recent years.[9] Many researchers and psychiatrists now recognize that depression is far more complex than a simple chemical imbalance. New theories have emerged that recognize factors such as emotional trauma, environmental factors, glutamatergic dysfunction, and inflammation as potential causes of depression.

In short, depression is a complex web of interweaving causes and effects, both psychological and physiological. While scientists know from research that SSRIs and other antidepressants certainly have an effect in alleviating depression, the actual pharmacology behind the medications is far more unclear. Why do some respond to medication negatively? Why do some not respond at all? Because these questions are so intimately tied with genetic and biochemical factors, they are very difficult to address in a comprehensive manner.

These observations lead to two important points: First, depression is such a complex disorder that we don’t yet know the best way to treat it with medication. Second, SSRIs may be somewhat effective in alleviating depression, but we don’t completely understand why they work the way they do. Because the root causes of depression are still somewhat uncharted territory, exploration of new treatments that work differently than SSRIs is very important. By pioneering these treatments and observing their effects, the puzzle pieces that make up the full picture of depression can be pieced together into a comprehensive model.

Topographs of average amplitude at 10-12 Hz showing increased high-frequency alpha in patients receiving NSI-189 at Day 28. Differences scores comparing conditions show most significant differences between total subjects receiving NSI-189 (left) vs. Placebo (right) in the left posterior temporal and parietal regions.

Some researchers, like those at Neuralstem, have noticed a correlation between reduced hippocampal volume and increased incidence of Major Depressive Disorder.[10] According to this theory, NSI-189 could potentially be a remedy to those suffering from depression by contributing to the growth of the patient’s hippocampus. Because the hippocampus is also so closely associated with memory, NSI-189 also has the potential to impact cognition.

This “hippocampal” model of depression is still in its infancy, and NSI-189 is one of the first drugs being researched that uses this specific form of treatment. Although it is known that NSI-189 increases hippocampal volume, the exact mechanism underlying this effect is still unsure. The results of the phase 1b trial even suggested that NSI-189s effect on hippocampal volume was not as drastic as that which was seen in animal studies.[11] Whether or not the increase of hippocampal volume persists after ceasing the medication remains to be determined. As the research and experimentation with NSI-189 continue, new research will shed light on this model for depression, and the medical community will be better able to understand the correlation between depression and hippocampal volume.

Purported Benefits

As mentioned above, the potential benefits of NSI-189 are:

Improvement in behavioral responses associated with depression.[12]

Reversal of hippocampal atrophy.[13]

May enhance memory and cognition through increase neurogenesis, particularly in depressed subjects.

Positive effects may persist after treatment ceases.[14]

Subjective Experiences

Because NSI-189 is still in its infancy as a clinical treatment for MDD and cognitive disorders, anecdotal information is important for those determining if they want to try NSI-189. This community poll conducted by /u/MisterYouAreSoDumb on /r/nootropics is useful for seeing various users’ experiences with NSI-189

A Reddit user, Code_of_Error, relayed his experience with NSI-189 in a post on reddit[15]:

I have been on NSI-189 Phosphate for three weeks now. I take 40mg orally once per day. I used to take it sublingually, but I learned that doing so may be counterproductive due to the possibility that too much is absorbed. Apparently, 40mg-80mg ORALLY was the sweet spot in clinical trials, so sublingual administration has too many unknowns to be worth it. Albeit, the freebase form is a different story. Anyway, I started exploring this substance in hopes of counteracting my chronic brain fog, slight depersonalization, anhedonia, general feelings of haziness, and slow cognition. Most notably, I have noticed an intensification of emotions, as well as pleasure. The first few days, I felt the inclination to tear up at every positive emotion. It felt ridiculous, but that has mostly leveled out. Although I am only three weeks in, I notice I am more inclined to look forward to plans. I am quicker to laugh and socialize. Prior to NSI-189, every emotion I experienced felt like nothing more than background noise. Now a days, all of my emotions feel more genuine, as if they’re at the forefront of my brain. When I experience anxiety, I no longer feel so dissociated from it. When I feel joy, it tends to last longer. Although these new perspectives are scary, I welcome the change. My default state of mind tends to be slightly perkier as well. I will admit that I am more guided by my emotions than I have been in years, and I am totally enabling it. I don’t recommend falling in love while on this substance. However, this substance is bringing me closer to my long-lost inner feelings. The effects aren’t perfect, and I still often feel that irritating haze (i.e., brain fog/dulled-out sensation/whatever ambiguous symptoms) to a degree, but I hope that my mental issues continue to improve as I stay on this. I’ve certainly made strides. Interestingly, I have noticed that I better able to “feel” the effects of nootropics while on this as well. Caffeine has a much more profound effect on me (comparable to when I first started using it), and the effects of tianeptine are as potent as ever. Again, I feel as if this speaks MORE to NSI-189’s ability to make you feel and less to its ability to reduce tolerance. Lastly, I would venture to say I am bit sharper mentally, and less likely to experience “cluttering” when I go to speak. Side effect wise, I only experience a mild fluttering (almost like a twitch) directly behind the inner half of my right eyebrow. Other than that, no headaches. I may have a mild reduction in sex drive, but nothing too troubling. Overall, I am looking forward to staying on this drug for a while. My mental symptoms are nowhere near gone, but I see enough benefits to keep going. Like many people who try an under-researched compound intended for depression, I feel as if I have little to lose.

This is the experience of flare1028us, another reddit user:[16]

Personally, I’ve found NSI-189 to be very useful. I’m taking 50mg freebase once daily in the morning. The acute effects for me are a gentle wave of calmness, improved long-term memory, and notably improved vision. The improved vision, as another redditor put it, is like my vision being “zoomed out” by 5%, like having a slightly larger field of view. Improved memory is the strong point of this substance. I find myself having vivid recollection of memories going back to my single digit ages. This has also allowed me to remember times when I encountered some of the same struggles I have to this day, and how I handled them – I feel better equipped to tackle them with better memory of what did and didn’t work in the past. As far as side effects, child-like emotions are coming on fairly strong. This is both good and bad. The good is that the sense of wonderment that we experience as children has come forth again, the bad being somewhat immature initial emotional responses. For example, jealousy – on a very childish level. It’s not debilitating, but it’s something to be mindful of. Speaking of being mindful, it has gotten a whole lot easier to practice mindfulness meditation and commit experiences I’ve gained through it to long(er) term memory. Interactions: Cannabis now gives me a mild headache, but if the high is balanced well (sometimes I’ll add some sublingual CBD), it is a very useful state of mind – for me it’s like being high with a better ability to remember the observations I make about my decisions and behavior that I may not come to so quickly in other states of mind. I tried taking piracetam once on NSI, and I’m never doing it again. Total dysphoria for most of the day from 3.5g piracetam in the morning. This stuff is supposed to reset piracetam tolerance, but I won’t be testing that until I’m off NSI-189 for a while. Tianeptine (sodium and sulfate) feels like it meshes really well with NSI-189, along with neurogenic peptides – took 200ug NA-Semax Amidate (sub-q) with NSI and went to yoga class (pretty intense class too). That was a level of control I would love to be able to gain every time I exercise in general. Hope this helps, I’m still waking up – I’ll answer questions if you have them

Conclusion

If NSI-189 proves to be an effective treatment for Major Depressive Disorder, it could have a potentially large impact on the direction of depression medication in the upcoming years. The long-standing dominance of SSRI drugs in the treatment of depression has left many wondering just how much longer it will be before the next major breakthrough occurs in depression treatment.

A novel drug like NSI-189 could be the answer, and the studies concerning NSI-189 also give us a useful glimpse into the correlations between depression, hippocampal volume, and cognition. As we move further into the 21st century, the scientific community will undoubtedly continue to map more accurately the territory that is the human mind.